This present invention relates to the field of audio/video playback devices and in particular, to a playback device that supports playing back data that is encoded in more than one format.
A playback apparatus receives from a data source that delivers audio and/or video data. The data source may be of very different nature; for example, it may be hidden behind a data interface if the data are received from the Internet or another data network via a personal computer (PC). Other examples of such data sources are compact data storage in which the data are stored (e.g., magnetically, optically, electronically, or on another principle) and converted during readout into an electronic data stream by suitable devices. Also suitable for use as compact data sources are solid-state memories, because such memories do not require a mechanical drive.
Data from the data source is converted to an error corrected data stream, and fed to an output decoder that separates the data stream into the respective signal components and, if necessary, converts the latter from digital to analog form. These signal components are then fed to a playback transducer (e.g., headphones, loudspeakers, etc.). In the case of video signals, the playback transducer may be a television receiver, a multimedia apparatus, or a simple video display on the playback apparatus.
CDs are reasonably priced devices for storing audio data, and have the benefit of being rewriteable (i.e., CD-RW). The original data is frequently streamed from the Internet. To permit the use of commercially available audio playback apparatus, the data must be stored according to submitted standards, for example according to the xe2x80x9cSony-Philips Red/Blue Bookxe2x80x9d.
The transmission, storage, and reproduction of data, particularly of audio data, in accordance with these standardized data formats is very common. However, it has the disadvantage that these standardized data formats frequently do not provide for data compression or only provide for relatively little data compression, so that they do not make optimum use of the existing storage space. On the other hand, there are techniques in which the level of compression can be chosen in a wide range. Pure voice applications allow a higher compression level than high-quality music reproduction. Such compression and coding techniques are known, for example, by the acronym xe2x80x9cMPEGxe2x80x9d, and are used, for example, in the optical storage of video and audio signals for a DVD system. It is desirable to take advantage of these data compression techniques, while retaining the proven recording, storage, and playback system as far as possible. In particular, a playback apparatus is desirable that is suitable for the reproduction of at least one improved data format and conventional or mixed data formats.
An object of the present invention is provide a playback apparatus that processes data from data sources with at least one specific code that is different from the conventional code, while retaining many conventional components.
Additional objects include providing a suitable storage device, a suitable data format, and a programming device adapted to the data format.
A playback apparatus of the present invention includes a code converter that is coupled to a data source. This code converter converts the data stream of this device, whose data format cannot be decoded by a conventional decoder. The code converter provides a data format that is processed by an output decoder to form playback signals. The code converter does not have to convert all of the data from the data source; it suffices that it convert particular portions of the received data stream into a form suitable for deriving the playback signals.
If the playback apparatus recognizes and processes two or more data formats, it is desirable to provide in parallel signal path to the code converter that includes a buffer. Without temporal compensation, in case of a switchover, the data routed directly to the output decoder would not fit in with the data passed through the code converter. As a result, without temporal compensation during a transitional period the output decoder may provide erroneous playback signals.
Control of the signal paths for the output decoder can be implemented simply by switching the signal paths manually. A more convenient control technique is an electronically activatable control unit that identifies particular data formats with a detector circuit and then effects the switchover automatically.
For consumer applications, compact, exchangeable storage devices are required as transportable data sources. Optical and magnetic storage devices generally require a mechanical drive, and thus a motor controller, with which the read rate is adapted to the respective data format. An error-detecting device is incorporated, and during the occurrence of errors in one of the data streams the error detecting device generates an error signal that disables the output decoder for at least the duration of the disturbance.
To achieve as uniform a data stream as possible (e.g., to compensate for a non-uniform read operation or to compensate for packet data formats containing a further data format in an interleaved form) buffers may be provided for the respective data stream.
If two or more data formats are identified and processed, it may be permissible, for example, that the recorded data is compressed in whole or in part. This increases the flexibility of the entire playback system. Whether the uncompressed and/or compressed data correspond to a standardized data format is important only inasmuch as the data formats must be adapted to the output decoder or the code converter. This requires, of course, that this be taken into account already during the recording of the data. Suitable programming or write devices, also known for compact disks by the term xe2x80x9cburnersxe2x80x9d, must define these readable data formats for the data to be stored.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.